- ungrateful, thankless, unthankful - not feeling or showing gratitude; "ungrateful heirs"; "How sharper than a serpent's tooth it is / To have a thankless child!"- Shakespeare
Antonyms: grateful, thankful, appreciative, glad
- ungrateful - disagreeable; "I will not perform the ungrateful task of comparing cases of failure"- Abraham Lincoln
Antonym: pleasant (indirect, via unpleasant)